"smartthings" presence sensor

I'm curious if anyone can figure out how this device works. It's not a PIR sensor - they sell that, but it's a separate device. This presence sensor is a uniquely identifiable dongle the person or dog wears, and the hub senses whether this dongle is within range (50-100 feet). What kind of technology are they using? The dongle seems to be powered via cell type battery, so there's some kind of transmission. Probably not RFID? Interested in coming up with something similar using Arduino mini pros.


Know when your kids get home from school, when Fido leaves the house through the doggy door, or when your spouse's car rolls up to the driveway.


It's a ZigBee radio that sends check-ins every so often to a hub/router. If hub hears messages then the tag is there, if there are no messages after a certain amount of time then the tag is gone.